The present invention relates to a transmission and reception apparatus and method for use in a radio communication system, and more particularly to a transmission and reception apparatus and method having only one phase-locked loop circuit, which is capable of providing local oscillation frequencies for upconversion and downconversion, as well as carrier frequencies for modulation and demodulation by utilizing only one phase-locked loop circuit.
U.S. Pat. No. 4,212,013 issued to Biethan on Jun. 8, 1980 discloses a general duplex-transmitter-receiver arrangement wherein only one oscillator is utilized for the transmitter and receiver, resulting in a considerable simplification of technical problems and a reduction in financial outlay. We have found that in the practice of this circuit a separate oscillator should be utilized for a transmission demodulator and a reception filter, respectively; consequently, the circuit for implementing a transceiver will be relatively complex, and concomitantly expensive in its construction.
U.S. Pat. No. 5,036,327 issued to Dannenberg on Jun. 30, 1991 discloses a radar receiver and transmitter using a single oscillator frequency shift keyed system. In Dannenburg '327, the oscillator shifts between a pulsed output frequency and a local frequency such that the system can transmit at one frequency and shift fast enough so that when an echo pulse is received, the transmitter is operating at the local frequency desired. While this type of conventional art provides advantages in its own right, we believe that an improved configuration can be contemplated.